It's possible. Any choice one makes involves risk. The Flow could stop. (ISIS could also invade and we could all be living under Sharia Law.) But getting called for an interview is even less of a guarantee. Then one must secure the job. Yes the flow is not a 100% sure but the idea that we will all be able to just pick the major airline and have a guarantee job is even more of a pipe dream. I don't know if I would recommend that someone make a lateral move to chase an airline with a flow but for a 1500 hr new hire that can choose to go to any number of regionals, all other things being equal, choosing a regional with flow gives them one more option than one without. Just because someone works for a regional with flow, they can still apply a job, attend a job fair and interview at another Major just like everyone else. They just have a back up plan. Personally, I always like having a little extra fuel.